In the case of motor vehicle air conditioners, the air cooled by the evaporator is forced out of a plurality of air vents into the interior of the vehicle. Usually for introduction into the interior of the vehicle, the portion of air passing through the left half of the evaporator flows out of the vent at the left (e.g. as opposed to the driver's seat), and the portion of air passing through the right half of the evaporator flows out of the vent at the right (e.g. as opposed to the passenger seat). Accordingly, if there is a temperature difference between the former portion of air and the latter portion of air, the riders are likely to feel discomfort. This problem becomes more pronounced since there is in recent years a tendency for the distance between the evaporator and the air vent to become smaller. The air temperature difference appears markedly with an increase in the lateral dimension of the evaporator.
To enable the left and right halves of the evaporator to provide air of uniform temperature, various refrigerant flow patterns have heretofore been contrived for use in evaporators. FIG. 13 shows an example of pattern. The illustrated evaporator 500 comprises a front heat exchange assembly 500A and a rear heat exchange assembly 500B which are adjacent to each other. Each of the heat exchange assemblies 500A, 500B comprises a pair of upper and lower horizontal headers 502 extending laterally, and a multiplicity of vertical refrigerant channels 503 arranged laterally at a spacing and each having an upper end connected to the upper header 502 and a lower end connected to the lower header 502. A refrigerant inlet 504 is provided at the left end of the upper header 502 of the rear heat exchange assembly 500B, and a refrigerant outlet 505 is provided at the left end of the upper header 502 of the front heat exchange assembly 500A. The upper headers 502 of the front and rear heat exchange assemblies 500A, 500B communicate with each other through communication tube portions 506 at portions thereof toward their right ends. The upper header 502 of the rear heat exchange assembly 500B is internally divided into two left and right portions by a vertical partition 502A so that the refrigerant flows downward through the channels 503 of the left half of the rear heat exchange assembly 500B, with the refrigerant flowing upward through the channels 503 of the right half of the rear heat exchange assembly 500B.
The upper header 502 of the front heat exchange assembly 500A is internally divided into two left and right portions by a vertical partition 502A so that the refrigerant flows downward through the channels 503 of the right half of the front heat exchange assembly 500A, with the refrigerant flowing upward through the channels 503 of he left half of the front heat exchange assembly 500A.
With the evaporator 500 of FIG. 13, the left half of the rear heat exchange assembly 500B wherein the refrigerant temperature is lowest, and the left half of the front heat exchange assembly 500A wherein the refrigerant temperature is highest are adjacent to each other along the direction of flow of air. Further the right half of the rear heat exchange assembly 500B wherein the refrigerant temperature is second lowest, and the right half of the front heat exchange assembly 500A wherein the refrigerant temperature is second highest are adjacent to each other along the direction of flow of air. Consequently, the portions of air A passing through the left and right halves respectively become substantially uniform in temperature.
With the evaporator 500 described, however, the portions of air A passing through the respective left and right halves of the evaporator 500 fail to become uniform in temperature to produce a temperature difference between the air portions forced out of the left and right vents respectively, when the clutch mechanism of the compressor is automatically disengaged, namely, when the flow of refrigerant through the evaporator 500 is temporarily halted, in order to prevent overcooling of air.
An object of the present invention is to provide an evaporator, for example, for use in motor vehicle air conditioners which provides air of uniform temperature as passed through the left and right halves thereof even when the clutch mechanism of the compressor is disengaged and which is therefore free of the likelihood of giving discomfort to the riders.